1. Field of the invention
The present invention relates to an inspection device for inspecting objects, particularly for explosives and/or explosive substances in travelers"" baggage.
2. Description of the Background Art
In view of heightened security requirements at airports and other public facilities, it is necessary to retrofit existing facilities, for example check-in counters in airports, with X-ray and inspection devices which can detect explosives and/or explosive substances, in particular. Oftentimes, only a small space is available for integration of such a retrofit device.
Known from EP 0 825 457 A2 is a tomographic scanner for detecting contraband items in passenger baggage, including explosives, which is moved about a piece of luggage. During the process, for instance, the piece of luggage is inspected from eight different directions in one radiation plane. Disadvantages of such scanners include the extensive mechanical structure and also the large installation space required.
EP 0 984 302 A1 describes a method and an apparatus of this type for examining luggage by X-ray scanning. The piece of luggage to be examined is moved on a conveyor belt into a scanner that, by means of a common arm, moves an X-ray unit and a detector unit relative to the luggage item. Scanning is performed in steps. For this purpose, the piece of luggage is conveyed in until its advance is stopped by a light signal. Then, the scanning motion over the luggage is started in the manner of a windshield wiper, wherein the X-ray unit and the detector unit are moved from one position to a second position. Thereafter, the piece of luggage is conveyed one step further in the transport direction and the X-ray unit and the detector unit are moved back from the second position to the first position for scanning. According to another embodiment, the X-ray unit and the detector unit are moved back and forth on a carriage transverse to the conveyor""s transport direction.
It is an object of the invention to provide an inspection device that works in a small space and is suitable for retrofitting.
According to the principles of this invention, an inspection device is used for the inspection of objects, whereby the object to be inspected is moved between at least one radiation source and one linear detector arrangement directed at the radiation source for scanning the stationary object. The radiation source and the detector arrangement are then moved in parallel over the object so that the object is scanned in the direction of and opposite to the transport direction of the object. During a first scan, the object is scanned with low-energy radiation, and during a second scan the object is scanned with high-energy radiation.
Because the available space within a separate piece of equipment is very small, the invention is based on the idea of using this space at least as a scanning area, around which at least one movable radiation source is arranged, at which a detector arrangement is directed that can be moved mechanically independently of the radiation source. In this context, the radiation source and also the detector arrangement can be moved parallel to and simultaneously with one another by mechanically or electrically coupled means, such as actuators. The synchronous movement is controlled and monitored with the aid of a computer.
The detector arrangement can include multiple detector pairs that are accommodated in a linear detector.
To create a usable radiation tunnel in this limited space, existing equipment components of the separate piece of equipment that is not part of the inspection device, are integrated into the inspection device, or vice versa. To this end, a shield, for example in the form of a hood, is placed ahead of the scanning area and on or around the system component of the separate piece of equipment. In the event that at least one system component of the equipment following the available scanning area is also integrated, it is also possible to place shielding on or around this system component. Frequently, the direct integration into a shielded housing of the inspection system is offered. In this way, at least one system component or an entire section of a piece of equipment that is functionally separate from the inspection system can be used, and thus in a larger sense becomes a part of the inspection device without removal of the system component itself from the actual equipment and without limitation of its actual functional use.
In a further embodiment of the invention, a closable curtain or roller shutter is integrated in the shield, which, in a preferred variant, is attached at the entrance or beginning of the shield. Moreover, provision can be made to install a camera in order to monitor the system components for proper function, that are covered by the shield.
In a further embodiment of the invention, the at least one radiation source is switched on when the object has been advanced into the scanning area. Before the object reaches the end of the scanning area, the advance in the transport direction is stopped so that the object is in a position of rest for the scanning process. The object is scanned in two directions, opposite to the transport direction and in the transport direction. At the first scan, for example, the object is exposed to low-energy radiation and at the subsequent scan, it is exposed to high-energy radiation. The individual image segments thus recorded are recorded separately, and one of them is mirrored so that together they produce a single, pixel-precise image segment for this scanned portion of the object that is analyzed and, for example, displayed as an image of the object in a known manner.
If only one radiation source is used, it must be switched over each time to provide the different radiation energies.
In another advantageous embodiment, two radiation sources may be integrated into the inspection device.